Expandable introducer sheath and method

ABSTRACT

One embodiment is directed to a system for deploying a device to a distal location across a vessel, comprising an elongate introducer sheath tubing member comprising open-cell fibrous wall material defining a lumen therethrough, wherein in a collapsed configuration the sheath has a first cross-sectional outer diameter and a first lumen inner diameter, and in an expanded configuration, the sheath has a second cross-sectional outer diameter and a second lumen inner diameter; and a substantially non-porous expandable layer coupled to a proximal portion of sheath and configured to prevent fluids present in the lumen from crossing the fibrous wall material. Also disclosed is a delivery assembly comprising an obturator which releasably captures the distal portion of an introducer sheath which obturator can be removed after the sheath is deployed to a desired location.

RELATED APPLICATION DATA

The present application is a continuation of U.S. patent applicationSer. No. 14/934,767, filed Nov. 6, 2015, which is a continuation-in-partof and claims the benefit under 35 U.S.C. § 120 of U.S. Patentapplication Ser. No. 14/276,952, filed May 13, 2014, and of Ser. No.13/673,898, filed Nov. 9, 2012, and Ser. No. 13/673,911, filed Nov. 9,2012, each of which claim the benefit of U.S. Provisional PatentApplication Ser. Nos. 61/717,575, filed Oct. 23, 2012, 61/558,397, filedNov. 10, 2011 and 61/558,357 filed Nov. 10, 2011, each of which isincorporated by reference herein in its entirety. The presentapplication also claims the benefit under 35 U.S.C. § 119 of U.S.Provisional Application Nos. 61/824,471, filed May 17, 2013 and61/822,204, filed May 10, 2013, and the benefit under 35 U.S.C. § 120 ofU.S. patent application Ser. No. 14/274,563, filed May 9, 2014, each ofwhich is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to medical interventionsconducted through vessels such as the major arteries, and moreparticularly to access and deployment configurations for conductingpercutaneous procedures such as percutaneous valve replacement whereinan introducer sheath may be utilized to provide minimally-invasivevascular access for passing instruments, prostheses, and otherstructures.

BACKGROUND

Gaining access to the heart and other parts of the cardiovascularanatomy is a continued challenge in cardiovascular medicine. Forexample, conventional open-surgical procedures for accomplishing taskssuch as valve replacement generally involve a thoracotomy and/orcreation of one or more access ports across the wall of the heartitself, which is relatively highly invasive and therefore undesirable.Recent progress has been made in the area of catheter-based percutaneousintervention, wherein instrumentation, such as catheters, guidewires,and prostheses, are brought to the heart, brain, or other tissuestructures associated with the cardiovascular system through the vesselsconnected to such structures. These vascular pathways may be quitetortuous and geometrically small, and thus one of the challenges withpercutaneous procedures lies in gaining access, conducting the desiredinterventional and/or diagnostic procedures, and removing the pertinentinstrumentation, without damaging the vasculature or associated anatomy.Conventionally with percutaneous procedures, introducer and dilator setssuch as that (2) depicted in FIG. 1 , have been utilized to provide ausable access conduit through an arteriotomy or other surgical access tothe vasculature. For procedures on large, relatively straight, andrelatively undiseased vessels, such configurations may be adequate, butfrequently cardiovascular diagnostic and/or interventional proceduresare conducted on diseased cardiovascular systems and in tortuousanatomy. There is a need for better access tools and procedures, whichmay be utilized to establish vascular access in a relatively efficientgeometric package (ie., in a collapsed state), be expanded in situ asnecessary to pass instrumentation, prostheses, or other structures (forexample, the un-expanded delivery size of a. CoreValve® aortic valveprosthesis available from Medtronic, Inc. is approximately 18 French;the un-expanded delivery size of a Sapien® valve available from EdwardsLifesciences, Inc. is between 18 and 24 French, depending upon whichsize is utilized), and to be re-collapsed before or during withdrawal sothat the associated anatomy is not undesirably loaded or damaged duringsuch withdrawal.

Such outer sizes do not allow for a conventional guide catheter to beinserted as a protective layer between the tools and the tissue, andtherefore the standard of care has become direct insertion of the valveinstrumentation through the diseased vessels to reach the targetlocation within or adjacent to the heart. Another complicating factorwith such interventions is the fact that it is likely that the aortathrough which the devices will be advanced will be diseased (one recentstudy concluded that 61% of patients over 65 years of age will severeaortic valve stenosis also have severe aortic atherosclerosis; Osrandek,et al., American Journal of Cardiology, 2009; 103:713-717). Thiscomplicated surgical paradigm has led some clinical researchers tobelieve that elevated stroke rates associated with such procedures maybe related to the physical insertion of large interventional toolsthrough the diseased vessels and concomitant scraping or micro-scrapingaction of the tools against the diseased vessel walls, which results inbreaking portions of plaque loose and allowing these to flow with theblood stream into the brain and other undesirable landing places. Thereis a need for a configuration where a relatively thin, but protectivesheath-like member can be put in place to guide the interventional toolsand prosthesis while mitigating load concentrations and/or scraping orabrasion of the interior of the subject vessels. Various embodiments ofthe subject invention address these challenges with expandableintroducer sheath configurations.

SUMMARY

One embodiment of the present invention is directed to improvinghemostasis at the access site of an expandable introducer sheath in ablood vessel. Other embodiments are directed to the proximal region ofthe expandable introducer sheaths as disclosed in more detail herein.The use of a braid structure as the expandable portion of the sheath incombination with a dilator nose cone is another embodiment of thepresent invention. In other embodiments, improved radiopacity structureand improved shape stability structures are provided.

Such embodiments are directed to a system for deploying a device to adistal location across a vessel, comprising an elongate introducersheath tubing member comprising open-cell fibrous wall material defininga lumen therethrough, wherein in a collapsed configuration the sheathhas a first cross-sectional outer diameter and a first lumen innerdiameter, and in an expanded configuration, the sheath has a secondcross-sectional outer diameter and a second lumen inner diameter; and asubstantially non-porous expandable layer coupled to a proximal portionof sheath and configured to prevent fluids present in the lumen fromcrossing the fibrous wall material. In the collapsed configuration, thesheath may be configured to be advanced across at least a portion of thevessel to a position adjacent the distal location without substantialsize interference between the first cross sectional outer diameter ofthe sheath and an inner diameter profile of a lumen of the vessel. Uponpositioning the collapsed configuration to the desired position relativeto the distal location, the sheath may be configured to be expanded tothe expanded configuration to facilitate passage of one or morerelatively large diameter structures through the lumen that are largerin diameter than the first cross sectional outer diameter. Uponcompletion of passage of the one or more relatively large diameterstructures, the sheath may be configured to be collapsed back to thecollapsed configuration. The first lumen inner diameter may be equal tobetween about 0 mm and about 4 mm. The second lumen inner diameter maybe equal to between about 4 mm and about 7 mm. The system further maycomprise one or more radio-opaque markers coupled to the sheath andconfigured to assist an operator observing fluoroscopy with positioningof the sheath relative to the vessel. The open-cell fibrous wallmaterial may comprise a matrix of fibers. The matrix of fibers may bearranged in a braided pattern. The fibers may comprise a polymericmaterial. The polymeric material may be selected from the groupconsisting of: polyester, polyamide, polypropylene, and copolymersthereof. The fibers each may have a diameter of between about 0.003inches and about 0.015 inches. The matrix of fibers may be configured tofunction to prevent expansion of the sheath beyond the secondcross-sectional outer diameter. The matrix of fibers may be configuredto bias the sheath to remain in the collapsed configuration until it isurged into the expanded configuration by passage of a structure throughthe lumen. The matrix of fibers may be configured to locally expandaround the structure passed through the lumen, and then to locallyre-collapse as the structure passes to an adjacent portion of the lumen.The substantially non-porous expandable layer may comprise a flexiblepolymeric material selected from the group consisting of: siliconerubber, olefin block copolymers, and copolymers thereof. The matrix offibers may define pores across the wall material which have a diameterbetween about 0.002 inches and about 0.20 inches. The system further maycomprise an inner liner member operatively coupled through the lumen ofthe elongate introducer sheath tubing member to define an inner workinglumen, the inner liner member configured to structurally reinforce thetubing member and facilitate relative motion between structures whichmaybe passed through the inner working lumen. The substantiallynon-porous expandable layer may be configured to extend from a proximalend of the elongate introducer sheath tubing member for a length ofabout 10 centimeters distally. The device may comprise an implantableprosthesis selected to be passed through the expandable sheath to thedistal location across the vessel. The implantable prosthesis maycomprise a cardiac valve prosthesis. The matrix of fibers may comprise amesh pattern. The system further may comprise a tensioning memberoperatively coupled to at least a portion of the matrix of fibers andconfigured to maintain such portion in a relaxed configuration, thetensioning member comprising a proximal portion configured to bemanually tensioned or relaxed by an operator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates various aspects of a conventional introducer anddilator kit for cardiovascular intervention.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J, 2K, 2L, 2M. 2N and 2Oillustrate various aspects of an inventive expandable introducer sheaththat may be used in conducting various cardiovascular procedures.

FIG. 3 illustrates various aspects of a minimally invasive accesstechnique in accordance with the present invention.

FIG. 4 illustrates various aspects of a minimally invasive accesstechnique in accordance with the present invention.

FIG. 5 illustrates various aspects of a minimally invasive surgicalaccess technique in accordance with the present invention.

FIG. 6 illustrates various aspects of a minimally invasive surgicalaccess technique in accordance with the present invention.

FIG. 7 illustrates various aspects of a minimally invasive surgicalaccess technique in accordance with the present invention.

FIG. 8 illustrates various aspects of a minimally invasive surgicalaccess technique in accordance with the present invention.

FIG. 9 illustrates various aspects of a minimally invasive surgicalaccess technique in accordance with the present invention.

FIG. 10 illustrates various aspects of a minimally invasive surgicalaccess technique in accordance with the present invention.

FIG. 11 illustrates various aspects of a minimally invasive surgicalaccess technique in accordance with the present invention.

FIG. 12 illustrates various aspects of a minimally invasive surgicalaccess technique in accordance with the present invention.

FIG. 13 illustrates an embodiment of the present invention in which theintroducer sheath assembly is provided with a proximal portion which ismore rigid than the distal portion of the sheath and with a dilatorassembly.

FIGS. 14A and 14B illustrate the embodiment of FIG. 13 in assembledform.

FIGS. 15A and 15B illustrate the structure of the dilator assembly ofthe device illustrated in FIG. 13 .

FIGS. 16A, 16B, 16C, 16D, 16E, and 16F illustrate the structure of thedilator tip, dilator shaft, and dilator sheath of the device of FIG. 13.

FIG. 17 illustrates an exemplary location for a radiopaque element inthe sheath and a hemostatic valve on the hub of the sheath assembly.

FIGS. 18A, 18B, 18C, 18D, 18E and 18F illustrate various meshconfigurations.

FIGS. 19A, 19A, 19B, 19C, 19D, 19E and 19F illustrate the clip which maybe used in combination with the sheath assembly.

FIGS. 20A and 20B illustrate, respectively, the mesh of the sheath whennot under tension and when under tension.

FIG. 21 illustrates the relevant anatomy with the sheath assemblydeployed in the vasculature.

FIGS. 22A, 22B, 22C and 22D illustrate the sequential movement of adevice through the sheath as the device is being deployed.

FIGS. 23, 24A, 24B, 25A, 25B, 26, 27A and 27B illustrate variousembodiments of the proximal section of the sheath.

FIGS. 28, 29A, 29B, 30A and 30B illustrate various configurations of thedistal section of the sheath.

FIGS. 31A, 31B, 31C and 31D illustrate various hemostatic valveconstructions which may be used with the sheath assembly.

DETAILED DESCRIPTION

Referring again to FIG. 1 , a conventional introducer sheath and dilatorkit (2) is depicted comprising an elongate dilator (4) with a proximalluer assembly (6); the dilator is configured to be inserted into theworking lumen (56) of the introducer sheath through a proximal sealcoupled to a hub (12) structure, which is also coupled to an extensiontube with stopcock (8), which may be utilized for infusion of fluidsinto the introducer lumen (56), for example. The conventional introducersheath will comprise an elongate tubular member (10) coupled proximallyto the hub (12) and being made from a relatively non-expandablepolymeric material or combination of polymeric materials, which resultsin introducer sheaths which are selected for their off-the-shelf workinglumen (56) diameter (i.e., they generally are not considered to haveexpandable diametric dimensions). Certain trocars and introducercatheters have been produced with expandable diametric geometries, butthey have been limited in their expandability due to the constraints ofhoop stress and friction (i.e., with a relatively low-modulus or evenrubber-like material, diametric expansion will be at least linearlyproportional to hoop stress in the expanded sheath material, which isproportional to frictional loads—which generally results in a usefulexpandability limit, beyond which too large a load is required todevelop relative motion between structures being passed through theworking lumen and the sheath which defines the working lumen).

Referring to FIG. 2A, one embodiment of an expandable introducer sheathto address these challenges is depicted, wherein the introducer sheathtubing member or assembly (14) comprises a plurality of braided fibersarranged in a braided or mesh pattern to form an open-cell fibrous wallmaterial comprising the sheath tubing member, which defines theintroducer working lumen (56). In one embodiment the distal portion (88)of the introducer sheath tubing member (14) comprises the open-cellfibrous wall material in its porous form without a nonporous coating,while a portion of the proximal portion (86), such as about the proximal10 centimeters, of the introducer sheath tubing member (14) is coatedwith a substantially non-porous expandable layer to assist withpreventing bleeding when the sheath is installed in a patient with theproximal portion extending transcutaneously out of thesurgically-created wound (such as an arteriotomy).

Referring to FIG. 2B, a braiding configuration (16) is depicted whereinsingle strands (20) of fibrous material are braided with each other,such as in one of the depicted patterns of FIG. 2D, 2E, or 2F (36, 38,or 40, respectively) to allow for significant diametric expandabilityand contractibility of the overall fiber/mesh assembly due to availablerelative motion between the fibers in an open-cell braidedconfiguration. In other words, it is the available micro-motion of thefibers of the braided pattern relative to each other that allows forrelatively low-load expandability and contractibility of the overallconstruct. This relative motion may be somewhat decreased when thefibrous assembly is combined with other structures, such as a nonporouscoating, which is the reason that in one embodiment, wherein maximumexpandability and contractibility is preferred, such nonporous coatingis only featured on the proximal aspect, or in another embodiment, notat all (i.e., there is no nonporous coating in such embodiment, andproximal bleed-through at the percutaneous access site may be mitigatedby another means such as gauze compression or a very thin andhighly-expandable lubricious sleeve that is not directly coupled to eachportion of the surface of the braided assembly, but is essentiallylooped around the bulk structure only with a light hoop stress). Theintersection angle (24) of intersecting fibers within the woven,braided, or mesh pattern will change with collapse or expansion of theoverall structure, and may be selected to affirmatively limit the lowerbounds of collapse diameter, as well as the upper bounds of expansiondiameter.

FIG. 2C depicts another braiding assembly (18) wherein each of thebraided fibers actually comprises a plurality of parallel fibers groupedtogether (22); the pattern of FIG. 2C has groups of approximately threesmall fibers travelling the woven, braided, or meshed pattern together.

U.S. Pat. Nos. 4,954,126; 4,655,771; 5,527,282; 5,061,275 and 5,221,261disclose braided mesh configurations suitable for use in the presentinvention and are incorporated by reference herein in their entireties.These helical body configurations include a plurality of fibers each ofwhich extends in a helix configuration along the center line of thehelical body as a common axis, the fibers defining a radiallyself-expanding body, which comprises a first number of fibers having acommon direction of winding but being axially displaced relative to eachother and crossing a second number of fibers also axially displacedrelative to each other but having an opposite direction of winding.

In one embodiment, the fibers may comprise a polymeric material such aspolyester, polyamide, polypropylene, or copolymers thereof. In oneembodiment the fibers each may have a cross sectional diameter ofbetween about 0.003 inches and about 0.015 inches. In one embodiment thebraiding, mesh, or weave pattern may produce pores in the expandablesheath wall material which have a diameter between about 0.002 inchesand about 0.20 inches. In one embodiment a nonporous coating layer onthe proximal portion of the expandable sheath assembly may comprise aflexible polymeric material such as silicone rubber, olefin blockcopolymers, and/or copolymers thereof.

When the braided fiber assemblies such as assemblies (16, 18) aretensioned (i.e., from either end), they will decrease in overallgeometry as the fibers comprising such assemblies move relative to eachother; similarly, when such assemblies are compressed, they willincrease in overall geometry. This factor may be controllably utilizedto assist with delivery and use of the subject elongate instrument. Forexample, referring to FIG. 26 , in one embodiment, an elongate loadingmember (46), such as a pull-wire or push-wire (which may also be calleda pushrod), may be operatively coupled between the distal end (42) ofthe introducer sheath tubing member (14), such as by direct mechanicalcoupling to a distal ring member (44) coupled to the distal tip (42) ofthe introducer sheath tubing member (14) and proximal coupling to aproximal control interface (48) such as a pull or push handle configuredto allow an operator to manually apply tensile or compressive loads (50)to the elongate loading member (46). Such a coupling configurationallows for manually-actuated and controlled expansion or contraction ofthe introducer sheath tubing member (14) from a proximal location.Referring ahead to FIG. 2N, other associated structures, such as adilator assembly or portions thereof, and/or a temporary locking member(80), may be utilized to place an introducer sheath tubing member (14)into a sustained tensile loading configuration (FIG. 2N illustrates anembodiment utilizing a locking member 80 to lock two portions of adilator assembly (an inner dilator member 64 and an outer dilator member66) into a loading configuration against each other, with the innerdilator member in tension and outer dilator member in compression, suchthat a distal portion of the sheath tubing member 14 remainsintercoupled in between such dilator members 64, 66, and such that theintroducer sheath tubing member 14 may be actively and sustainablypulled into tension to retain a decreased cross sectional diameter untilthe locking member 80 is removed) to assist with insertion or removal ofthe introducer sheath tubing member (14) relative to the associatedanatomy.

Referring to FIG. 2H, in another embodiment, it may be desirable toinsert a tubular liner member (52), such as a polymeric tubular member,defining a tubular liner member lumen therethrough, to assist withinsertion and/or withdrawal of structures through the introducer sheathtubing member (14). The tubular liner member may be selected to have ahigher structural modulus than that of the introducer sheath tubingmember (14) to effectively provide some rigidity and kink resistance tothe overall assembly. The inner diameter of the tubular liner member(52) preferably will be sized to define a working lumen therethroughthat will accommodate selected instrumentation without substantialexpansion of the tubular liner member (52), and insertion of the tubularliner member (52) generally will urge the associated introducer sheathtubing member (14) from a relatively collapsed configuration to arelatively expanded configuration; removal of the tubular liner memberwill allow the introducer sheath tubing member (14) to return to therelatively collapsed configuration; this is demonstrated in thedifference in outer diameters (60, 62) of the depicted introducer sheathtubing member (14) in FIG. 2H with the tubular liner member (52) inplace urging the introducer sheath tubing member (14) to the moreexpanded configuration, and FIG. 2I with the tubular liner memberremoved, allowing the introducer sheath tubing member (14) to return tothe relatively collapsed configuration.

Referring to FIG. 2J, an assembly is shown utilizing an introducersheath tubing member (14) along with other structures in acardiovascular access configuration. In this embodiment, a two-partdilator assembly is used, as described above in reference to FIG. 2N.The assembly comprises an inner dilator assembly (comprised of an innerelongate dilator member 64 fixedly coupled to a distal dilator tip 68having a tapered distal portion 72; the proximal portion of the innerelongate dilator member is fitted through the seal of the hub 12 andcoupled proximally to a luer assembly 6) movably coupled to an outerelongate dilator member (66). This dilator assembly is fitted throughthe hub (12) and through the introducer sheath tubing member (14), withthe exception of the tapered distal portion (74) of the introducersheath tubing member (14), which is coupled into a tapered recessedinner geometry (70) of the proximal aspect of the dilator tip member(68) in a slightly compressed manner. As described above and furtherbelow in reference to FIG. 2N, with the distal portion of the sheathtubing member (14) intercoupled between the inverse taper (70) of thedilator tip member (68) and the tapered distal portion (78) of the outerdilator member (66), the sheath tubing member (14) may be tensioned toreduce cross sectional geometry by further inserting the outer dilatormember (66) while the distal portion of the sheath tubing member (14)remains pinched and therefore coupled between the dilator tip member(68) and tapered end portion (78) of the outer dilator member (66);without this pinching constraint, the distal portion of the sheathtubing member (14) may be allowed to freely escape from the dilator tipmember (68).

FIG. 2K illustrates an inner dilator assembly comprising an innerelongate dilator member (64) coupled to a dilator tip member (68) havinga tapered distal portion (72) and a tapered proximal interior surface(70) for restrainably coupling with another tapered member which may beinserted into it, such as the distally tapered (78) outer dilator member(66) of FIG. 2L, or the distally tapered (74) introducer sheath tubingmember (14) of FIG. 2M. FIG. 2M also illustrates that the outer dilatormember (66—shown in dashed) may be inserted through the lumen of theintroducer sheath tubing member (14) to capture a distal portion of theintroducer sheath tubing member (14) in a pinched coupling mannerbetween the outer dilator member (66) and the dilator tip member (68)which is coupled to the inner dilator member (64—also dashed), asdescribed in reference to FIG. 2N.

As described above, FIG. 2N illustrates that a locking member (80) maybe temporarily positioned between the hub (12) and a proximal portion ofa dilator member (64) to place an introducer sheath tubing member (14)in tension between the hub (12) and dilator tip (68) to reduce theoverall cross-sectional geometry of the introducer sheath tubing member(14) for improved insertion/withdrawal performance.

Referring to FIG. 2O, an interventional assembly (84), such asvariations described in U.S. Patent Application Ser. No. 61/822,204,incorporated by reference herein in its entirety, the assembly (84)comprising an elongate tubular member (82), may be utilized with anintroducer sheath tubing member (14) as described herein.

Referring to FIGS. 3-12 , various configurations for proceduresutilizing an expandable introducer sheath such as those described aboveare illustrated.

Referring to FIG. 3 , after preoperative diagnostics and patientpreparation (202), vascular access may be established, such as by asurgically-created arteriotomy cut-down, and a guidewire may be inserted(204), such as an 0.035″ diameter guidewire. A collapsed form (i.e.,with a first inner lumen diameter of between about 0 mm and about 4 mm)of an expandable introducer assembly comprising an open-cell braidedfiber tube or tubular assembly may be inserted (206). In one embodimentthe expandable fiber assembly may be expanded to provide inner workinglumen diameters of between about 4 mm and about 7 mm, for example. Withthe tubular introducer sheath assembly in place, the associated dilatorassembly may be removed (208). In one embodiment this may beaccomplished by advancing the distal portion of the dilator assemblyrelative to the intercoupled braided expandable sheath to release thedistal end of the expandable sheath from tension between the dilatordistal portion and the hub (as described above in reference to FIG. 2N),allowing it to expand to provide an inner diameter sufficient to allowthe dilator distal portion to be proximally withdrawn through theworking lumen I inner diameter of the expandable sheath. At such point,the expandable sheath is in place relatively unconstrained, and theguidewire remains in place through the working lumen of the expandablesheath. In one embodiment one or more radio-opaque markers may becoupled to the expandable sheath assembly to assist with imagingconfirmation of deployment location. Referring again to FIG. 3 ,interventional and/or diagnostic tools and/or prostheses may be insertedthrough the expandable sheath, thereby further expanding the sheath(210). Expansion of the expandable sheath may be localized, such thatafter a relatively large member is passed through and past a givenportion of the sheath, that portion re-collapses, at least partially.After utilization of the interventional and/or diagnostic tools has beencompleted, they may be withdrawn proximally until there are removed, andthe expandable sheath may be allowed to further collapse or contract indiameter (212). Subsequently the collapsed expandable sheath andguidewire may be proximally withdrawn (214) and the surgical accessclosed (216).

Referring to FIG. 4 , an embodiment similar to that of FIG. 3 isdepicted, with the exception that steps 210 and 212 of the embodiment ofFIG. 3 have been replaced with steps 218, 220, 222, and 224, wherein atubular liner is inserted to occupy at least a portion of the expandableintroducer lumen, and to form a lumen within the liner which may beutilized as the new working lumen (218); tools for interventional and/ordiagnostic procedure steps may be inserted through the liner lumen whilethe procedure is conducted (220); after the procedure has been completedthe tools may be withdrawn out through the liner lumen (222), andsubsequently the tubular liner itself may be withdrawn (224) to allowthe expandable sheath to form a more collapsed geometry for withdrawalof such expandable sheath (214).

FIG. 5 illustrates an embodiment similar to that of FIG. 3 , with theexception that an additional step is included (226) wherein an elongateloading member may be tensioned to place the braided fibrous expandablesheath into compression, thereby forcibly increasing the diameter of theassociated defined introducer lumen for easier passage of structuresthrough such introducer lumen.

FIG. 6 illustrates an embodiment similar to that of FIG. 3 , with theexception that insertion of the expandable sheath assembly isfacilitated by forcibly minimizing the diametric geometry of theexpandable sheath using a push-wire to create tensile loading of theexpandable sheath during insertion (228, 230).

FIG. 7 combines the differences of the embodiments of FIGS. 5 and 6relative to that of FIG. 3 , both in the same embodiment/procedure, suchthat tension is controllably applied to minimize the outer geometry ofthe expandable sheath member during insertion (228, 230), and such thatcompression is controllably applied to maximize the geometry of theexpandable sheath member for insertion of instrumentation therethrough(226) FIG. 8 illustrates an embodiment similar to that of FIG. 4 whereina tubular member or liner may be inserted into the expandable sheath toassist with sheath expansion and insertability I retractability ofinstrumentation (218, 220, 222, 224); also combined into this embodimentis the aforementioned aspect of creating compressive loading of theexpandable sheath member to maximize the geometry of the expandablesheath member for insertion of instrumentation therethrough (226).

FIG. 9 illustrates an embodiment similar to that of FIG. 4 wherein atubular member or liner may be inserted into the expandable sheath toassist with sheath expansion and insertability I retractability ofinstrumentation (218, 220, 222, 224); also combined into this embodimentis the aforementioned aspect of creating tensile loading of theexpandable sheath member to minimize the geometry of the expandablesheath member for insertion or withdrawal from the vasculature (228,230).

FIG. 10 illustrates an embodiment similar to that of FIG. 4 wherein atubular member or liner may be inserted into the expandable sheath toassist with sheath expansion and insertability I retractability ofinstrumentation (218, 220, 222, 224); also combined into this embodimentis the aforementioned aspect of creating compressive loading of theexpandable sheath member to maximize the geometry of the expandablesheath member for insertion of instrumentation therethrough (226), aswell as the aforementioned aspect of creating tensile loading of theexpandable sheath member to minimize the geometry of the expandablesheath member for insertion or withdrawal from the vasculature (228,230).

FIG. 11 illustrates an embodiment similar to that of FIG. 7 , withadditional emphasis on having a dilator assembly comprising two or moreparts (232), such as that shown in FIG. 2J.

Similarly, FIG. 12 illustrates an embodiment similar to that of FIG. 10, with additional emphasis on having a dilator assembly comprising twoor more parts (232), such as that shown in FIG. 2J.

FIG. 13 illustrates an exploded view 300 of another embodiment of anintroducer sheath assembly, a dilator assembly, and a clip in which theintroducer sheath assembly 301 is provided with a proximal section 303which is more rigid than distal flex section 304. The dilator assembly305 comprises dilator shaft 306, dilator sheath 307 and dilator tip 308along with clip 309. As described below, when assembled, the elements ofFIG. 13 are arranged in the same general manner as illustrated in FIGS.2J-2N.

FIGS. 14A and 14B illustrate the introducer sheath assembly, dilatorassembly and clip of FIG. 13 in assembled form. As shown in thesefigures, the dilator shaft and dilator sheath of dilator assembly 305extend through a lumen in introducer sheath 301 and terminate in dilatortip 308 which extends distally from distal flex section 304 ofintroducer sheath 301. FIG. 14A also shows the location of clip 309 inrelation to hub 302 and clip lock recess 310 in hub 302. The fixationregion 311 of the mesh of distal flex section 304 to proximal section303 is also shown. FIG. 14B shows the location of the transversecross-section shown in FIG. 24A and FIG. 14B shows the location of thelongitudinal cross-section shown in FIG. 16E.

FIG. 15A shows dilator assembly 305 in an exploded view with dilatorsheath 307 shown separately from dilator shaft 306 and dilator tip 308.When assembled, dilator shaft 306 passes through the lumen 313 indilator sheath 307 and the proximal end of dilator shaft 306 is providedwith a luer lock 312. FIG. 15B shows the dilator assembly in assembledform and shows the location of the longitudinal cross-section shown inFIG. 16A. FIG. 15A also shows the external proximal bevel 314 and theexternal distal bevel 315 proximal portion 303 and the distal portion304, respectively, of dilator sheath 307.

FIG. 16A shows the longitudinal cross-section of the distal region ofthe dilator assembly according the section line shown in FIG. 15B. Asshown in FIG. 16A, the dilator shaft 306 extends into the proximalregion of dilator tip 308 and is affixed to tip 308 in an intermediateregion 319 of tip 308. As further shown in FIG. 16A, lumen 316 in thedilator tip is a continuation of lumen 365 in the dilator shaft. Dilatortip 308 is also provided with an internal bevel in its proximal regionwhich has a shape which is complementary to that of external distalbevel 315 on dilator sheath 307.

FIG. 16B illustrates the relationship of the dilator sheath 307 and thedistal flex section 304 with dilator tip 308 before the dilator sheathand distal flex section are advanced into the dilator tip 308. FIG. 16Cshows these elements after the dilator sheath and distal flex sectionhave been advanced into the dilator tip. FIGS. 16D-F show thisrelationship in a series of cross-sectional views. In FIG. 16D, as inFIG. 16B, the dilator sheath and the distal flex section have not yetbeen advanced into mesh entrapment region 320 and the distal flex meshis in a free state 321. In FIG. 16E, as in FIG. 16C, the dilator sheath307 and the distal flex mesh 304 have been advanced into mesh entrapmentregion 320 such that the mesh is gripped by the beveled internal wall317 of the dilator tip and the beveled external distal wall 315 of thedilator sheath such that the mesh is in the captured state 322. FIG. 16Fshows the same elements after the mesh has been placed under tension andis in tensioned state 323.

FIG. 17 illustrates sheath 301 and shows an exemplary location for aradiopaque element 325 which can be provided to improve visibility underfluoroscopy or other similar techniques. FIG. 17 also shows the locationof hemostatic valve 324 which, as indicated, is illustrated in moredetail in FIGS. 31A-D.

FIGS. 18A-E show various mesh configurations with radiopaque marker 326illustrated in FIG. 18A and radiopaque ring 327 illustrated in FIG. 18C.FIG. 18F shows radiopaque strand 328. A platinum or other radiopaquematerial could be used for strand 328. Alternatively, polymer strands inthe mesh could be filled with a radiopaque material such as bariumsulfate.

FIGS. 19A-F illustrate clip 309 in greater detail. FIG. 19A is aperspective view of clip 309 and shows handle 366, hub lock 367, hubengaging portion 368 and dilator housing compartment 369. FIGS. 19B-19Fillustrate the clip as viewed from various vantage points. FIG. 19B is aside view, FIG. 19C is a bottom view. FIG. 19D is a top view, FIG. 19Eis an end view as seen from the dilator engaging end and FIG. 19F is anend view as seen from the hub engaging end. In addition. FIG. 19Billustrates partition element 370 which separates the hub engagingportion of clip 309 from the dilator engaging portion 369. Also shownare the dilator sheath restraint 371 and the luer lock restraint 372which define sheath tensioning section 373. Luer lock restraint 372prevents distal displacement of the dialator shaft when the dilatorshaft slides distally until the luer lock 312 abuts luer lock restraint372.

FIG. 19C illustrates slot 374 in element 370 through which the dilatorassembly passes, slot 375 in dilator sheath restraint 371 and slot 376in luer lock restraint 372. FIG. 19D is a top view of clip 309. FIG. 19Eillustrates lock nub 377 which constrains removal of the dilator shaftfrom slot 376 when the device is assembled, but which permits removal ofthe dilator shaft when sufficient force is applied, as seen from thedilator engaging end of the clip. FIG. 19F illustrates the same elementsas seen from the hub engaging end of the clip.

The clip 309 is used to maintain the axial relationship of theintroducer sheath, dilator sheath and dilator shaft as shown in FIGS.14A and 14B. The clip tension sheath section 373 maintains therelationship between the distal bevel 315 of the dilator sheath and theproximal bevel 317 of the dilator tip. Section 368 of the clip 309maintains the relationship between the introducer sheath 301 and thedilator assembly 305 which is adapted to place the sheath under tensionwhich decreases the diameter of the distal flex section 304.

FIGS. 20A and 20B show, respectively, the distal flex mesh section 304in the distal captured state 322 when not under tension and the distalflex section under tension by reason of actuation of clip 309. As shownin FIG. 20A when clip 309 is not installed over hub 302, distal meshsection 304 is not under tension and is slack. The diameter of distalflex section 304 can very according to the design of the mesh. Forexample, the diameter of the mesh in its relaxed state could be the sameor similar to its diameter in the tensioned state. Furthermore, thediameter of the mesh in its relaxed state could be significantly largerin diameter than in the tensioned state such that, when tension isreleased, the mesh will self-expand. As further shown in FIG. 20A,dilator shaft is free to slide axially in dilator sheath 307 until theluer lock abuts the dilator sheath. When clip 309 is installed over hub302 as shown in FIG. 20B, dilator sheath 307 is no longer free to slidewithin hub 302, but rather is locked in place by dilator sheathrestraint 371 against which it abuts. However, dilator shaft 306 remainsfree to slide within dilator sheath 307 and is held in a proximallydisplaced location by luer lock restraint 372 which places mesh 304under tension and reduces its diameter. Conversely, when clip 309 isremoved from the sheath 301, the dilator shaft is free to move distallyand may be advanced in a distal direction until the dilator tip 308separates from the dilator sheath 307 to free the distal portion 304 ofthe sheath. When this is done, the dilator shaft 306 and dilator tip 308together with dilator sheath 307 may be withdrawn from the introducersheath. With introducer sheath 301 now being free of the dilatorassembly, a device to be deployed may be passed through the introducersheath and delivered to a desired location.

FIG. 21 illustrates the anatomy relevant to the present invention with adiagrammatic view showing an embodiment installed in a patient. Asshown, an expandable introducer 300 is introduced over guidewire 350 andenters the body at femoral artery access point 351 and enters the arteryat vessel puncture site 352. Guidewire 350 has previously been deployedthrough the femoral artery, the right common iliac 353 and through aorta354 until it reaches the ascending aorta as shown by the dotted line. Asshown in FIG. 21 , the expandable introducer is introduced into theright common iliac 353 and the aorta 354. In some cases, the expandableintroducer may be introduced into the ascending aorta 355.

FIGS. 22A-D illustrate the sequential movement of a transcatheter aorticvalve 356 through introducer sheath assembly 300 over guidewire 350. Inthe embodiment shown in FIG. 22A the transcatheter aortic valve 356 hasa diameter d1 which is larger than the unexpanded diameter d2 of theproximal portion 303 of the expandable introducer sheath which has beendeployed in femoral artery 357. After valve 356 passes through hub 302as shown in FIG. 22B, it causes proximal expandable sheath 303 to expandto an outer diameter d3. This proximal portion 303 may be designed tocollapse after the device 356 passes through it. In a differentembodiment shown in FIG. 22C the proximal relatively rigid section 303of introducer sheath 301 has a diameter large enough to permit passageof transaortic valve 356 which does not cause expansion of the sheathuntil it reaches flexible distal portion 304. At this point, theprogress of the valve 356 shown in the embodiments of FIG. 22A and FIG.22C causes the distal flexible mesh section 304 to expand locally asvalve 356 passes through the sheath until it reaches its deliverylocation. FIG. 22D shows transaortic valve 356 at a location distal fromthat shown in FIG. 22C. FIGS. 22C and 22D also show the mesh 304collapsing to a smaller diameter after valve 356 passes through it.Alternatively, if mesh 304 has a diameter in its relaxed state which isthe same or larger than its diameter in the expanded state, it will notcollapse after a device passes through it.

As shown in FIGS. 23-27B, the proximal semi-rigid section 303 can have alimited expansion capability. This expansion capability may be providedby providing proximal section 303 with a fold or plication 358 such asthat shown in the unexpanded state in FIG. 24A where proximal section303 has a diameter of d2 and FIG. 24B where proximal section 303 has anexpanded diameter d3. Similarly, in FIGS. 25A-26 the proximal section303 can comprise a helically wound coil 359 which may be covered with anexpandable membrane (not shown) or a seal 360 may be provided as shownin FIG. 26 . Alternatively, as shown in FIGS. 27A and 27B, the proximalsection 303 may comprise an external cover such as a membrane combinedwith expandable reinforcing rings 361 which will expand when placedunder pressure by a device such as a heart valve passing throughproximal section 303. The foregoing examples are not exhaustive.

Proximal semi-rigid section 303 can be fabricated in a variety ofadditional ways in which an expandable polymer tube can be reinforcedwith a metal or other material which either has no expansion capabilityor a limited expansion capability. Limited expansion capability can beimparted by coiled or braided structures which are embedded in a polymertube such as those disclosed in U.S. Pat. Nos. 5,527,282; 4,655,771;4,954,126; 5,061,275 and 5,221,261, the disclosures of which areincorporated by reference herein. A wide variety of polymers and metalsmay be used for these purposes, provided that the resulting structurewill substantially resist collapse. When so constructed, the proximalportion will provide more effective hemostasis at the access point suchas femoral artery access point 351 and the vessel puncture site 352 asshown in FIG. 21 , where the sheath intersects with and penetratesthrough tissue and the wall of a blood vessel.

FIGS. 28-30B illustrate in more detail examples of distal flex section304 which may be used in the present invention. FIG. 28 shows distalflex section having a sealed mesh end 362. FIGS. 29A and 29B illustratea distal flex section 304 provided with an anti-inversion seam 363.FIGS. 30A and 30B illustrate a distal flex section 304 provided with ananti-inversion spine 364. The anti-inversion elements provide extrasupport so that the mesh does not fold when devices are moved throughthe lumen of mesh 304.

FIGS. 31A-31D show various types of hemostasis valves 324 which may beused in conjunction proximal hub 302 as more generally indicated in FIG.17 . Mom specifically, FIG. 31A illustrates a valve comprising a neckeddown portion 365. FIG. 31B shows a valve combined with a rummel 366which can be used to control its diameter. FIG. 361C illustrates a fluidfilled toroidal balloon sphincter 367 which is provided with a fill tube368 and a shut off valve 369. FIG. 31D illustrates a valve assembly inwhich a wire spring clip 370 is used to control the diameter of thevalve.

In use, the embodiment of the present invention illustrated in FIGS.13-31D proceeds through the steps of assembling the dilator assembly 305and the sheath assembly 301 by entrapping the distal region of mesh 304between dilator tip 308 and the distal portion of dilator sheath 307 asshown, for example, in FIGS. 16D-16F. Clip 309 is then used to placemesh 304 under tension as shown in FIGS. 20A and 20B. This causes mesh304 to assume a collapsed configuration by reason of the tension placedupon it. This combined assembly of sheath 301 and dilator assembly 305is then introduced into the vascular system as shown in FIG. 21 asdescribed above. When the distal region of the sheath is at its desiredlocation in the vasculature, the clip is removed and the dilator sheathis disengaged from the dilator tip by advancing the dilator tip awayfrom the distal region of the dilator sheath by moving dilator shaft 306distally. This frees the distal portion of mesh 304 which allows it toexpand which, in turn, permits removal of dilator assembly 305 from thesheath assembly 301. A medical device such as a transcatheter aorticvalve 356 can then be advanced through the proximal region 303 and thedistal region 304 of the sheath assembly as shown in FIGS. 22A-22D. Oncethe medical device has been deployed, the sheath assembly 301 can beremoved from the patient along with guidewire 350 to complete the devicedeployment procedure.

Various exemplary embodiments of the invention are described herein.Reference is made to these examples in a non-limiting sense. They amprovided to illustrate more broadly applicable aspects of the invention.Various changes may be made to the invention described and equivalentsmay be substituted without departing from the true spirit and scope ofthe invention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processact(s) or step(s) to the objective(s), spirit or scope of the presentinvention. Further, as will be appreciated by those with skill in theart that each of the individual variations described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinventions. All such modifications are intended to be within the scopeof claims associated with this disclosure.

Any of the devices described for carrying out the subject diagnostic orinterventional procedures may be provided in packaged combination foruse in executing such interventions. These supply “kits” may furtherinclude instructions for use and be packaged in sterile trays orcontainers as commonly employed for such purposes.

The invention includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the end user. In other words,the “providing” act merely requires the end user obtain, access,approach, position, set-up, activate, power-up or otherwise act toprovide the requisite device in the subject method. Methods recitedherein may be carried out in any order of the recited events which islogically possible, as well as in the recited order of events.

Exemplary aspects of the invention, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present invention, these may be appreciated inconnection with the above-referenced patents and publications as well asgenerally known or appreciated by those with skill in the art. Forexample, one with skill in the art will appreciate that one or morelubricious coatings (e.g., hydrophilic polymers such aspolyvinylpyrrolidone-based compositions, fluoropolymers such astetrafluoroethylene, hydrophilic gel or silicones) may be used inconnection with various portions of the devices, such as relativelylarge interfacial surfaces of movably coupled parts, if desired, forexample, to facilitate low friction manipulation or advancement of suchobjects relative to other portions of the instrumentation or nearbytissue structures. The same may hold true with respect to method-basedaspects of the invention in terms of additional acts as commonly orlogically employed.

In addition, though the invention has been described in reference toseveral examples optionally incorporating various features, theinvention is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the invention. Variouschanges may be made to the invention described and equivalents (whetherrecited herein or not included for the sake of some brevity) may besubstituted without departing from the true spirit and scope of theinvention. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a.” “an,” “said.” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

The invention claimed is:
 1. A method comprising: providing anintroducer sheath comprising: a proximal rigid section; a distal flexsection; and a hub; inserting a dilator assembly through a lumen of theintroducer sheath; gripping a distal region of the distal flex sectionbetween a distal tip of the dilator assembly and a dilator sheath of thedilator assembly; placing the introducer sheath under tension tocollapse the distal flex section; and attaching a clip to the hub tomaintain an axial relationship of the introducer sheath, the distal tip,and the dilator sheath.
 2. The method of claim 1 wherein the distal flexsection is attached to the proximal rigid section at a fixation region.3. The method of claim 1 wherein prior to the gripping, the distalregion of the distal flex section is in a free state.
 4. The method ofclaim 3 wherein subsequent the gripping, the distal region of the distalflex section is in a captured state.
 5. The method of claim 4 whereinsubsequent to the placing, the distal flex section is in a tensionedstate.
 6. The method of claim 5 wherein the distal flex section has asmaller diameter in the tensioned state than in the free state.
 7. Themethod of claim 1 wherein the proximal rigid section is more rigid thanthe distal flex section.
 8. The method of claim 1 wherein the grippingcomprises advancing the distal region of the distal flex section into abeveled internal wall of the distal tip.
 9. The method of claim 8wherein the gripping further comprises advancing a beveled external wallof the dilator sheath into the beveled internal wall of the distal tipsuch that the distal region of the distal flex section is gripped in anentrapment region.
 10. The method of claim 1 further comprising:advancing the introducer sheath over a guidewire; removing the clip tofree the distal region of the distal flex section from between thedistal tip and the dilator sheath; and withdrawing the dilator assemblyfrom the introducer sheath.
 11. The method of claim 10 furthercomprising: passing a device through the introducer sheath to a distallocation in a blood vessel.
 12. A method comprising: deploying anintroducer sheath in a blood vessel; passing a device through a proximalrigid section of the introducer sheath into a distal flex section of theintroducer sheath; passing the device through the distal flex section toa delivery location within the blood vessel, wherein the device causesthe distal flex section to locally expand solely at a location where thedevice is positioned within the distal flex section; and preventing thedistal flex section from inverting during the passing the device throughthe distal flex section.
 13. The method of claim 12 wherein the proximalrigid section does not expand during the passing of the device throughthe proximal rigid section.
 14. The method of claim 12 wherein theproximal rigid section expands during passing of the device through theproximal rigid section.
 15. The method of claim 14 wherein thepreventing the distal flex section from inverting comprises providingthe distal flex section with an anti-inversion element.
 16. An assemblycomprising: an introducer sheath comprising: a proximal rigid section; adistal flex section; and a hub; a dilator assembly within a lumen of theintroducer sheath, the dilator assembly comprising: a dilator sheath;and a distal tip; a clip attached to the hub to maintain an axialrelationship of the introducer sheath, the distal tip, and the dilatorsheath, the clip placing the distal flex section under tension to assumea collapsed configuration.
 17. The assembly of claim 16 wherein theproximal rigid section comprises a fold that provides a limitedexpansion capability for the proximal rigid section.
 18. The assembly ofclaim 16 wherein the proximal rigid section comprises a helical woundcoil that provides a limited expansion capability for the proximal rigidsection.
 19. The assembly of claim 16 wherein the proximal rigid sectioncomprises expandable reinforcing rings that provides a limited expansioncapability for the proximal rigid section.
 20. The assembly of claim 16wherein the distal flex section comprises an anti-inversion element.